1. Technical Field of the Invention
The present invention relates to a shrouding system for a high speed gear train, and more particularly, to a system for minimizing gear windage and churning power losses within a gear train.
2. Description of the Prior Art
High speed gear trains generate a substantial amount of heat due to windage and churning of the gears resulting in significant power losses of the gear train. Gear related power losses are due in part to windage currents pumped by the gears and the churning of oil between meshing gears within the gear train. The desirability to minimize the weight of components, especially in aircraft environments, results in gear trains operating at higher speeds thereby increasing windage losses. Windage losses typically increase as a cube function of gear speed. Therefore, power losses particularly in gear trains of aircraft continue to be a problem.
Shrouding of the gear train, or portions thereof, has been proposed to reduce gear churning losses. Typically, a large clearance is utilized between the gear and shroud, and the gear may extend below the cooling fluid level. Churning losses have also been reduced through the reduction in the amount of oil or cooling fluid flow to the gears. However, even if a low rate is reached where the oil flow is sufficient to cool the gears, power losses within the gear train are still unacceptably high. Other methods for the dissipation of heat within the gear train result in further power losses. Therefore, a need has thus risen for a shrouding system for a high speed gear train for the minimization of gear windage and churning power losses. A need has further arisen for a shrouding system for the efficient circulation of cooling fluid around the gears within a gear train.